In a conventional stapler, a staple mounting magazine housing a staple connecting assembly is fixed to a horizontal base by a main shaft and an operating handle that is rotatable around the main shaft is provided. Then, if the operating handle is rotated around the main shaft, a staple mounted in the staple mounting magazine is brought into contact with a surface of a paper bundle placed on the horizontal base before the paper is stapled.
However, since the operating handle rotates around a specific one point, the inclination of a staple pushed out of the staple mounting magazine is not constant depending on thickness of the paper bundle, posing a possibility of irregularly stapled paper bundle.
Staplers constructed to be able to push legs of a staple perpendicularly to the paper to prevent such a possibility are available and an invention relating to such staplers is described, for example, in Patent Document 1.
Patent Document 1 discloses a stapler constructed to “hold a paper receiving rear table in a horizontal position and a paper receiving front table slightly tilted forward, cause a guide plate set up in a rear end portion of one side wall of a slider to project by inserting the guide plate through an opening of the paper receiving rear table to make lower end portions of operating pieces to attach to/detach from the guide plate, and move the slider backward by pressing the guide plate via the lower end portions of the operating pieces when a handle is operated by pressure, thereby releasing right and left ends of a bending table retaining body placed on the front end portions of both side walls of the slider so that legs of a staple are bent slightly obliquely in parallel and flatly.”
According to Patent Document 1, “since a pedestal, the paper receiving rear table, and a frame are centrally connected by one main shaft, the handle is connected to a portion of the frame via a spindle, and so there is only one fulcrum of the main shaft, the frame and a staple bending table attached to the paper receiving rear table move together in a backward direction when stapling by separating a staple through a handle operation. Thus, a positional relationship between a paper bundle and staples sandwiched by the frame and the staple bending table is maintained so that staples can always be bent precisely and smoothly.”
Some types of conventional staplers have a structure in which the staple mounting magazine is pivotally supported with respect to the horizontal base and the operating handle is pivotally supported with respect to the staple mounting magazine.
However, if the operating handle is rotated, a shaft portion that pivotally supports the operating handle with respect to the staple mounting magazine will lift up the staple mounting magazine by the principle of leverage. Thus, a stapler whose operating handle can be rotated with a small force while preventing the staple mounting magazine from being lifted up by rotation of the operating handle is preferable. An invention relating to such staplers is described, for example, in Patent Document 2.
Patent Document 2 discloses a stapler in which a handle frame 6 is pivotally supported by a third spindle with respect to a support piece provided on a horizontal base (base frame). According to Patent Document 2, the stapler is considered to be able to push a staple into a paper bundle easily with a small force because an operating handle is rotated.
Further, conventional staplers have a paper end guide provided so that one edge of a paper bundle can be aligned before pushing staples to positions to be stapled. Inventions relating to the paper end guide are described, for example, in Patent Document 3 and Patent Document 4.
“A paper end guide reciprocating back and forth is slidably provided” is described in 10th to 12th lines in a right column on page 2 of Patent Document 3. According to Patent Document 3, the paper end guide is considered to be able to align one edge of a paper bundle and also, by moving the paper end guide, to adjust a stapling position of a staple in the paper bundle to a desired position apart from one edge of the paper bundle with a predetermined distance.
“By lifting up the pressing blade guide 17 of the staple mounting magazine, a convex portion of the pressing blade guide engaged with a concave portion of a notch of the outer frame 11 is removed from the concave portion to move up and the back side of a staple discharge port is opened so that a staple hooked on a staple outlet is spontaneously discharged from the staple discharge port by an energizing force of a rail caused by a spring” is described in 23rd line on page 13 to 9th line on page 14 of Patent Document 4.
Patent Document 1: Japanese Utility Model Registration No. 3,031,392
Patent Document 2: Japanese Patent Application Laid-Open No. 2005-034966.
Patent Document 3: Japanese Patent Application Laid-Open No. 6-285772
Patent Document 4: PCT Publication No. WO 98/039143.